INTRACELLULAR PH REGULATION IN ISCHEMIC MYOCARDIUM

缺血心肌细胞内 PH 值调节

• 批准号: 2028950
• 负责人: JOANNE S INGWALL
• 金额: $ 19.21万
• 依托单位: BRIGHAM AND WOMEN'S HOSPITAL
• 依托单位国家: 美国
• 财政年份: 1997
• 资助国家: 美国
• 起止时间: 1997-02-01 至 2000-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2028950
• 关键词: 5' nucleotidase; acidity /alkalinity; adenine nucleotides; adenosine monophosphate; adenosine triphosphate; enzyme activity; heart function; intracellular transport; isolation perfusion; laboratory rat; myocardial ischemia /hypoxia; myocardium; nuclear magnetic resonance spectroscopy; nucleotide metabolism

DESCRIPTION (adapted from the applicant's abstract): By combining results from 31P NMR spectroscopy of the rat heart and conventional analysis of freeze-clamped tissue the applicant has obtained evidence for a regulatory role for intracellular pH (pHi) on adenine nucleotide resynthesis in myocardium improved by ischemia. Specifically, by combining high-flow hypoxia (where pHi does not fall below 7.0) and ischemia (where pH falls to 6), the applicant found that low pHi leads to greater accumulation of AMP during ischemia and to greater ATP resynthesis and improved functional recovery during reflow. Following 28 minutes of global normothermic ischemia, the amount of ATP synthesized upon reperfusion equals the amount of AMP that had accumulated during ischemia. Essentially all of the ATP resynthesized during reperfusion is via this mechanism. The applicant hypothesizes that the underlying mechanism for this observation is inhibition of cytoplasmic AMP-specific 5'-nucleotidase (5'-NT) by H+, thereby, preventing the conversion of AMP to adenosine. If this is the case, low pHi protects the myocardium by preserving a significant fraction of the cytosolic adenine nucleotide pool during ischemia. Using NMR spectroscopy of isolated perfused rat heart and conventional biochemical tools, the applicant will pursue three specific aims which focus on the consequences of acidic pH on the capacity of the ischemic myocardium to synthesize ATP during reperfusion: (1) to define in vivo regulation of 5'-NT activity; (2) to determine the time course of activation, inhibition and reactivation of 5'-NT activity; (3) to define the relationship among pHi, ATP and return of cardiac function.

描述（改编自申请人的摘要）：通过结合结果 从大鼠心脏的31 P NMR光谱和常规分析， 申请人已获得监管证据， 细胞内pH（pHi）对腺嘌呤核苷酸再合成的作用 心肌缺血改善。 具体而言，通过结合高流量 缺氧（其中pHi不低于7.0）和缺血（其中pH福尔斯降至 6），申请人发现低pHi导致AMP的更大积累 在缺血期间，ATP再合成增加， 在回流期间恢复。 经过28分钟的全身正常体温 缺血时，再灌注时合成的ATP量等于 在局部缺血期间积累的AMP。 基本上所有的ATP 在再灌注期间再合成是通过这种机制。 申请人 假设这种观察的潜在机制是 H+对细胞质AMP特异性5 ′-核苷酸酶（5 ′-NT）抑制， 从而防止AMP转化为腺苷。 如果是这种 例，低pHi通过保留显著部分来保护心肌 细胞内腺嘌呤核苷酸库的变化。 使用NMR 离体灌流大鼠心脏光谱和常规生化 工具，申请人将追求三个具体目标，重点是 酸性pH值对缺血性心肌细胞 再灌注过程中ATP合成：（1）确定ATP的体内调节 5 '-NT活性;（2）测定激活、抑制的时程 和5 '-NT活性的重新激活;（3）确定 pHi、ATP和心脏功能恢复。